31

EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 16, 2025, 10:01:15 PM »

Power off, across the diode but with your DMM in ohm mode. You should read around 2k.

Ok power off measuring resistance with a meter probe on either side of D1 gives 0.0ohms
D2 gives 2.8kohms

 both relays and diodes were double checked for proper orientation and are ok. 

Also I did not have to desolder/resolder the relay

32

EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by JPK on November 16, 2025, 09:38:08 AM »

Power off, across the diode but with your DMM in ohm mode. You should read around 2k.

33

EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 16, 2025, 02:20:15 AM »

It looks like the relay coil is disconnected.
Check that the relay is in the correct direction (white line on the left).
Can you measure the coil resistance across the diode?
Did you have to desolder and remove the relay during assembly?
The relay may be damaged, try to replace it.

How do I measure coil resistance across the diode?

34

EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by JPK on November 15, 2025, 05:07:11 PM »

It looks like the relay coil is disconnected.
Check that the relay is in the correct direction (white line on the left).
Can you measure the coil resistance across the diode?
Did you have to desolder and remove the relay during assembly?
The relay may be damaged, try to replace it.

35

EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 14, 2025, 07:33:34 PM »

When I measure DC voltage across D1 putting a meter probe on either side of the diode, I get 32V when the EQ is is in XLR 

Both switched Off and PRE give me a DC voltage across D1 very low 0.02V

36

EQ573 Equaliser / Re: First three frequencies on the mid band not working

« Last post by JPK on November 14, 2025, 05:13:29 PM »

37

EQ573 Equaliser / Re: First three frequencies on the mid band not working

« Last post by distortionplus on November 13, 2025, 07:08:32 PM »

Check the solder joints of inductor L1, in particular the bottom left pad, near R35.

Fixed!!!!! Thank you so much for the fast response and very helpful advice!

38

EQ573 Equaliser / Re: First three frequencies on the mid band not working

« Last post by distortionplus on November 13, 2025, 06:34:54 PM »

On it - thank you!

39

EQ573 Equaliser / Re: First three frequencies on the mid band not working

« Last post by JPK on November 13, 2025, 04:55:25 PM »

Check the solder joints of inductor L1, in particular the bottom left pad, near R35.

40

EQ573 Equaliser / First three frequencies on the mid band not working

« Last post by distortionplus on November 13, 2025, 03:37:45 PM »

Hi,

I bought a pair of earlier 573s on Reverb, not fully working. I've ironed out many of the issues with relative ease but just come down to one last problem that I thought might be good to get some help on.

It's an EQ573-REV1.4

The first three frequencies on the mid band do nothing - the signal is unaffected by boost/cut, the EQ starts working as you would expect at 0.7 onwards.

0.27, 0.36 & 0.5 selections do nothing.

Any clues?

Thanks so much, the EQs sound really good and I'm looking forward to hopefully having them working 100%!